Process for preventing the formation of clinker rings



March 14, 1944. cQlFFU I 2,344,391

PROCESS FOR PREVENTING THE FORMATION OF CLINKER RINGS Filed April 22, 1941 9 I O 1. f 0

gwuem oom Patehted Mar. 14, 1944 PROCESS FOR. PREVENTING THE FORMA- TION OF CLINKER RINGS Pierre Coifl'u, Paris, France; vested in the Alien Property Gusto dian Application April 22, 1941, Serial No. 389,810 In Germany June 5, 1939 two sectors of carborundum bricks i, separated 2 Claims.

The use of rotary furnaces which are con tinuously fed with raw materials at the upper end and heated by a flame at the other end lead, particularly in the manufacture of cements, to the formation of an inner ring which progressively increases and finally obstructs the furnace.

The various known means for proceeding with the destruction of the said ring vary with the nature of the products being treated and the size of the furnace but all of them cause a deterioration of the refractory lining and frequent interruptions in the operation of the furnace.

' It has also been attempted to delay the forma-' tion of the ring by different means. Thus, for instance, by modifying the composition and the state of the raw materials introduced in the furnace. Such means generally cause an irregular operation of the furnace, either in modifying the comsition of the finished products obtained or by varying the heating process which consequently do not assure a perfectly regular operation and combustion and thus an economical production.

The present invention has for its objects a process which more effectively delays formation of the said ring and even in some cases prevents it without having the above mentiOned disadvantages, and which consists in systematically bringing to different temperatures various spots of the furnace lining located in the region in which the said ring is ordinarily being formed and in a same plane which is at right angles to the axis of revolution of the said furnace, so that the isothermal curves of the lining are no longer located, as is usually the case, substantially in planes at right angles to the said axis.

' As illustrating the invention I have shown diagrammatically on the accompanying drawing the preferred mode of carrying it out:

Fig. 1 is a vertical cross-section of a rotary furnace arranged for operation in accordance with the invention;

Fig. 2 is a vertical cross-section of a modified form of furnace for the same purpose;

Fig. 3 is a vertical longitudinal section of the same and Fig. 4 is a vertical cross-section showing operating means for effecting periodic change in speed of the furnace.

In the preferred embodiment of the said invention, the lining of the furnace, in the zone in which the ring is likely to be formed, is provided with zones constituted by a material having a thermal conductivity which is higher than that of the adjacent zones.

The lining of the said furnace is constituted by by two sectors of silico-aluminum bricks 2. The latter being of lower thermal conductivity, the corresponding furnace walls are hotter than the walls corresponding to the sectors 9.

In a second embodiment of the present invention, Figs. 2 and 3, the furnace is provided in the region in which the ring is likely to be formed, with a non-circular section, 1. e., a section in which some points are more remote than the others from the general axis of revolution of th furnace.

By way of example, the Figures 2 and 3 show two sections at right angles to each other of a furnace according to the said second embodiment.

The section of the said furnace is circular over most of the length of the furnace and is larger at 3 in the zone in which the ring is likely to be formed.

In such conditions, in the parts 3, which are most remote from theaxis, is obtained a temperature which is lower than that prevailing in the parts closer to the axis.

In both above embodiments, the means for solving the problem suggested, 1. e., the destruction of the rings, consist in special constructions of the furnace. The said means do not vary in a given furnace, whilst the position, shape and nature of the ring are at each time diiierent. The remedy is thus not exactly adapted to the evil.

On the contrary, in the third embodiment described hereunder, the remedy may be varied according to the evil.

In said third embodiment of the present invention, a difierence of temperature in the zone of formation of the ring is generated when it is desired to prevent the formation of the ring, by modifying the normal distribution of calories transferred to the lining by the heating device,

nace several times at each revolution, said slowing down being always produced at thetime at which one or more points of the furnace reach the highest point. Full stoppage for a very short time could also be provided at each revolution.

The mechanical embodiment of said controlled slowing down or stopping of the furnace only involves very simple mechanical or electrical problems, known by themselves. It would naturally be necessary to adjust the average speed of revolution of the furnace, so that its production will not be reduced.

As illustrating such an operating embodiment, Fig. 4 shows electrical feed lines 4 for a motor 5 which rotates the furnace 6 through a train of gearing I. The furnace carries an operating arm 8. This arm actuates a switch 8 by which the motor circuit is varied periodically to slow down or momentarily interrupt the rotation of the furnace.

I claim:

1. A process for preventing the formation of clinker rings in molten or clinkered materials such as cement in a rotary furnace comprising rotating said furnace about its axis constantly in the same direction and then diminishing the turning speed at certain predetermined intervals of time.

2. A process for preventing the formation of clinker rings in molten or clinkered materials such as cement in a rotary furnace comprising rotating said furnace about its axis in one direction only and then stopping said rotation for a predetermined time and at predetermined intervals of time.

PIERRE COIFFU. 

